Historian Kenneth Jackson posits four key factors that shaped the evolution of America’s suburbs: transportation technology, changing cultural values, a romantic connection to nature, and Jeff ersonian anti-urbanism. 3 Taken together, these elements would reconfi gure the geography of American cities over the next century and half, with the United States shifting from being a nation of relatively compact cities to one of decentralized metropolitan form. As a result, the post-1950 spatial trends are quite startling: from one-fourth of the total population living in the suburbs in 1950, to two-thirds of Americans in suburbs after 2010. 4
ink back to the 1800s. American cities were still densely populated and pedestrian in scale. People of all social classes and backgrounds
often lived alongside each other. But, over the next half century, the introduction of new forms of transportation technology-the steam ferry, horse car, cable car, and elevated rail-forever altered the spatial form of American cities. Each technological innovation built the momentum for a wholesale exodus of city dwellers from the original urban core. In the 1870s and 1880s, the fi rst “streetcar suburbs” of America, from Boston to San Francisco, allowed people to move away from increasingly crowded downtowns, with their congested warehouse and fi nancial zones, factories, and densely occupied immigrant tenement districts. Rail suburbs initiated what became the driving theme for modern American city-building: escape from the congestion, noise, and pollution of the traditional urban core. Ironically, that original desire to escape the impending environmental crisis of rapid industrial growth in the central city-air pollution, traffi c, and noise-would eventually reproduce another version of those problems on the urban periphery.